Multiple directories for VST/SF2/LV2/etc.

[JGHFunRun]

Enhancement Summary

Allow for the user to have multiple VST/SF2/LV2/etc. directories that are detected instead of just one. (also support for a custom LV2 directory is needed in general)

Justification

Many systems have at least 2 directories where VSTs and other plugins are installed, this would allow them to all be used instead of having to copy/move files around

[Spekular]

Duplicate of #4907, which is currently the third result when searching"multiple VST". The second result is #5433, which includes this as a sub issue.

These would be the first and second results before this issue was opened.

[JGHFunRun]

Sorry about that then I didn't see those I think I was searching other stuff I don't remember what it's been almost two months (and I only just saw it trying to find a different issue I opened)